Carburettors comprising an auxiliary device for cold starting



April 1965 A. L. MENNESSON CARBURETTORS COMPRISING AN AUXILIARY DEVICEFOR COLD STARTING Filed Dec. 18, 1962 III/II ban 'llllllw/Ille 'IIIIIId;

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INVENTOR- AA/D/FE '4 00/6 mam/w sY g' United States Patent Ofifice3,179,388 Patented Apr. 20, 1965 835,109 2 Claims. (Cl. 261-39) Thepresent invention relates to carburettors for internal combustionengines and in particular for motor car engines, comprising, for thestarting of said engines and the cold running thereof, an auxiliarydevice capable of increasing the fuel feed rate when the engine is cold,said device being operated by a bimetallic member subjected to thetemperature of an element which is heated simultaneously with theengine.

As it is known, such an auxiliary device may consist of an eccentricallypivoted valve member disposed in the inlet conduit of the carburettor,upstream of the orifices through which fuel is supplied to this conduit,said valve member being urged in the opening direction by the suction ofthe engine, against the action of said bimetallic member. This lastmentioned member generally consists of a spiral wound strip one end ofwhich is fixed whereas the other end is free and acts upon the auxiliaryvalve member, the element to the temperature of which said strip isresponsive being for instance heated by the exhaust gases of the engine,by the cooling water or by the lubricating oil of said engine, or beingan electrical resistor energized at the same time as the ignitioncircuit of the engine.

A drawback of such an auxiliary device is that when the vehicle runsover small distances and is stopped for a substantial time between therunning periods, the engine being then itself stopped, the bimetallicmember does not reach a sufliciently high temperature at the end ofthese running periods for placing the auxiliary starting device out ofaction for a sumciently long time. Therefore, some minutes afterstopping, the bimetallic member starts acting upon the starting deviceto restore it into operative position. It follows that, if the engine isstarted at this time, it makes use of the auxiliary starting device, atleast partly, Whereas it is still warm enough not to require theoperation thereof.

The object of the present invention is to obviate this drawback.

For this purpose, according to the present invention, the devicecomprises means capable of opposing to the displacement of the free endof the bimetallic member, in the vicinity of the position occupied bysaid end when said member is hot, a resistance greater in the directioncorresponding to a cooling of this member than in the opposed direction.

A preferred embodiment of the invention will be hereinafter describedwith reference to the appended drawings, given merely by way of example,and in which:

FIG. 1 is an elevational view, partly in section, of a carburettorprovided with a device according to the present invention forcontrolling the fuel rate in. the fuel and air mixture fed to aninternal combustion engine, the carburettor being shown in the coldrunning position;

FIG. 2 is a half section on the line II-II of FIG. 1;

FIGS. 3, 4 and 5 are views, similar to a portion of FIG. 1, and showingthe elements thereof in the respective posi tions they occupy accordingto three different conditions of operation;

FIG. 6 shows a curve illustrating the operation of a device according toFIGS. 1-5, the temperature being plotted in abscissas and the angularpositions of the free end of a bimetallic strip in ordinates.

The general construction of the carburettor proper may be of anysuitable kind. For instance, as shown, it comprises an air intake 1, anintake conduit 2 provided with a venturi 3 and with a throttle valve 4,a fuel feed conduit 5 provided with orifices 6 opening at the level ofthe venturi throat, the throttle valve 4 being-intended to be operatedby the driver.

Concerning the starting device, it comprises an eccentrically pivotedvalve 7 placed in the air intake 1 upstream of venturi 3 and rigid witha spindle 8 journalled in the wall of the air intake conduit. At one ofthe ends of this spindle 8 there is fixed a lever 9 carrying a finger 10engaged in the hook shaped free end 11a of a spiral wound bimetallicstrip 11 the inner end 11b of which is fixed on a finger 12. Strip 11 islocated in a casing 13, carrying finger 12 and where the temperature isfixed by a fluid (air or water) circulating in the vicinity of strip 11.An electric resistor may also be placed in casing 13 close to strip 11.Anyway the fluid or the resistor is at a temperature varying in the samemanner as that of the internal combustion engine.

When spiral wound strip 11 is cold (FIG. 1) its end 11a is located online X (corresponding to the angle A of FIG. 6) and valve member 7 is inthe closed position. When spiral strip 11 is sufficiently heated (FIG.3), its end 11a is located in the vicinity of line X (corresponding tothe angle A of FIG. 6) and valve 7 is fully open, the starting devicebeing then wholly out of action. When the end 11a of strip 11 movesbeyond line X for instance as far as line X (FIG. 3) corresponding toangle A (FIG. 6), auxiliary valve 7 is stopped by an abutment (notshown).

According to the present invention the device comprises means capable ofopposing, to the movement of the free end 11a of spiral wound strip 11,in the vicinity of the position occupied by said free end 11a when strip11 is hot, a resistance greater in the direction corresponding to thecooling of this strip (anti-clockwise direction) than in the opposed,i.e. the clockwise, direction. Advantageously, as shown, said meansconsist of a lever 14 pivoting about an axis 15 parallel to spindle 8,this lever being urged by a spring 16 and carrying a wedged-shaped, ornose, portion 17, the two opposed faces of which are adapted tocooperate alternately with the end 11a of strip 11.

l In the embodiment of the invention illustrated by the drawings, whenspiral strip 11 is heated, the end 11a of said strip comes to slidealong the left hand face of nose 17 until it escapes therefrom andpasses on the other side thereof, and, when this strip 11 is coolingdown, said strip end 11a, after coming into contact with the right handface of said nose portion 17 of lever 14, causes said lever to pivotabout its axis 15, this action being resiliently opposed by that ofspring 16.

Lever 14 cooperates with a fixed abutment 18, on one side, and, on theother side, with a push piece 19 slidable against the action of spring16, adjustable by means of a screw 20.

This system works as follows:

When the engine is started the elements of the device occupy theposition of FIG. 1. In this position spiral wound strip 11 keeps, as faras possible, valve 7 closed against the action of the suction created bythe engine. But, as bimetallic strip 11 is getting warm, it tends towind up audits end 11a is displaced in the clockwise direction. After agiven time said end 11a comes into contact'with the left hand face ofthe portion17 of lever 14 which cannot move since it is applied againstits abutment 18 and said strip end slides along this face until it islocated along line X corresponding to the vertical position of valvemember 7. But spiral wound strip 11 is free to wind up furtherinresponse to the rise of temperature,

its end lla moving past the end of nose 17 and coming into the positionshown by line X in FIG. 3.

If at this time the engine is stopped, spiral strip 11, which is nolonger being heated, should not come back too quickly into the positionof FIG. 1 or at least into a position ranging between X, and X whichwould corre spond to a partial closing of valve member 7 and wouldpermit the starting device to be again operated as soon as the engine isonce more started.

'Lever 14 then acts in the following manner (FIG. 4). When spiral strip111 is cooling down, it unwinds, that is to say its free end 11a movesin the anti-clockwise direction. Thisend 11a then comes, at a giventime, to bear upon the right hand face of the nose 17 of lever 14 (FIG.4), which face is perpendicular to the direction of movement of thestrip end 11a. Therefore,'in said position of FIG. 4, lever 14 does notexert any reaction tending to cause the end 11a of strip 11 to pass fromthe right hand side to the left hand side of nose 17. It is thereforenecessary for strip 11 to pivot lever 14, against the action of spring16, to bring said lever 14 into a position (such as that of FIG. 5)where the end 11a of strip 11 can slide along the right hand face ofnose 17, to move beyond the end of said nose and to come upon the lefthand side thereof. This is possible only if strip 11 exerts a sufficienteffort, that is to say if the temperature has reached, when decreased,,a value lower than that for which, during the preceding temperaturerise, the end lla of strip 11 has moved beyond the position indicated byline X To sum up, it will be seen that when, due to a rise of thetemperature, spiral strip 11 is wound up, i.e. when its end Illa movesin the clockwise direction,ait reaches position X for a giventemperature. But if it has moved beyond this position and thetemperature decreases,thus tending to move said strip end 11a inthe'anti-clockwise direction, it can move beyond position X only for atemperature much lower than that for which it exceeded this positionwhen rotating in the clockwise direction. s

The curve of FIG. 6 illustrates the operation of this device. In saidfigure the temperature T in centigrade degrees is plotted in abscissasand the angular position of the end 11a of bimetallic strip 1 1 isplotted in ordinates. ,The curve in solid lines corresponds toincreasing values of temperature T.

If it is supposed that the position X (angle equal to zero as designatedby A corresponds to a temperature of C. and the position X (angle A to atemperature of +45 C., a small horizontal curve portion is notedafter'this temperature, corresponding to the necessity forthe end 11a ofstrip 11 to reduce its radius so as to be able to move beyond the apexof nose 17. Then the angle increases asa function of the temperature forinstance up to a value A If then the temperature begins to decrease, thecurve is no longer the solid lines curve, but the curve in dotted lines.It Will be seen that for angle A (line X in FIG. 3), the end 11a ofstrip 11 comes back into contact with lever 14. At this time'a reductionof the temperature does not immediately reduce angle A. It is only whenspring 16 is sufficiently compressed, that suddenly the end 11a of strip11 moves beyond nose 17 (FIG. 5), which corresponds to the verticalportion of the curve in dotted lines of FIG. 6.

In the example illustrated by FIG. 6, during the heating up period valvemember 7 is in the vertical position, the starting device being then outof action for a temperature of strip 11 of 45 C. On the contrary, duringthe cooling down period strip 11 can act'upon valve '7 to move it intothe closed position only for a temperature of C.

When the strength of spring 16 isadjusted by means of screw 20, thecooling curve portion is modified for instance from'the shape shown indotted lines to that s 11a of strip 11 has released lever 14, this levercomes back into its initial position under the action of spring 16 andit is ready to act once more if the spiral wound strip 11 is once moreheated. t 7

Of course the bimetallic strip instead of being spiral wound might havethe shape of a helix or any other curve. a

In a generalmanner, while the above description discloses what is deemedto be a practical and efficient embodiment'of the invention, saidinvention is not limited thereto as there might be changes made in thearrangement, disposition and form of the parts without departing fromthe principle of the invention as comprehended within the scope of theappended claims.

What I claim is:

1. In a carburettor for an internal combustion engine, an auxiliarydevices of the type described which comprises, in combination, a frame,a choke valve movably carried by said frame for varying the fuel rate ofthe fuel and air mixture supplied by said car burettor, said choke valvehaving a closed position where the fuel rate is maximum and an openpositionswhere the fuel rate is lower, a bimetallic spiral stripresponsive to variations of said internal combustion engine temperature,said bimetallic spiral strip being fixed at its inner end to said frameabout an axis, the outer end of said bimetallic strip being movable withrespect to said frame between a cold state position and a hot stateposition along a given path of travel,

said bimetallic strip outer end being, operatively connected with saidchoke valve for gradually opening said choke valve from its closedposition when said temperature corresponds to the engine being cold toits open position when said temperature has raised to a given value, alever pivotedto said frame about an axis parallel to said firstmentioned axis, said lever having a wedgeshaped portion adapted tocooperate with said strip outer end and located between the cold stateposition and the hot state position of said bimetallic strip outer end,said wedge-shaped lever portion having a first'face turned toward saidbimetallic strip cold state position, and a second face turned towardsaid bimetallicstrip hot state position, said strip being so arrangedthat its outer end is out of contact with-said lever when the engine iscold and is applied against said first face of said lever wedgeshapedportion when the engine temperature has raised to said given value sothat said strip outer end can slide along said first face and beyond itto said second face of said wedge-shaped portion when the enginetemperature rises above said given value, said second face of said leverwedge-shaped portion being at least substantially perpendicular to thepath of travel of said strip outer end for said given position of saidlever, and spring means carried by said frame adapted resiliently tourge said lever in the direction opposed to that in which it is pushedby said strip outer end moving from its hot state position toward itscold state position, so as yieldingly to oppose the rotation of saidlever produced by the push of said strip outer end on said second faceof said lever wedge-shaped portion during a lowering of the enginetemperature.

2. In a carburettor for an internal combustion engine, an auxiliarydevice of the type described which comprises, in combination, a frame, achoke valve movably carried by said frame for varying the fuel rate ofthe fuel and air mixture supplied by said carburettor, said choke valve:having a closed position where the fuel rate is maximum and an openposition where the fuel rate is lower, a bimetallic spiral stripresponsive to variations of said internal combustion engine temperature,said bi metallic spiral strip being fixed at its inner end to said frameabout an axis, the outer end of said bimetallic strip being movable withrespect to said frame between a cold state position and a hot stateposition along a given path oftravel, said bimetallic strip outer endbeing operatively connected with said choke valve for gradually openingsaid choke valve from its closed position when said temperaturecorresponds tothe engine being cold to its open position when saidtemperature has raised to a given value, a lever pivoted to said frameabout an axis parallel to said first mentioned axis, said lever having awedge-shaped portion adapted to cooperate with said strip outer end andlocated between the cold state position and the hot state position ofsaid bimetallic strip outer end, said wedge-shaped lever portion havinga first face turned toward said bimetallic strip cold state position,and a second face turned toward said bimetallic strip hot stateposition, spring means carried by said frame adapted resiliently to urgesaid lever in the direction opposed to that in which it is pushed bysaid strip outer end moving fromits hot state position toward its coldstate position, and an abutment fixed with respect to said frame andadapted to cooperate with said lever to limit its displacement by saidspring means to a position such that said strip outer end is out ofcontact with said lever when the engine is cold and is applied againstsaid first face of said lever wedge-shaped portion when the enginetemperature has reached said given value, said first face being obliqueto the path of travel of said strip outer end so that said strip outerend can slide along said first face and beyond it to said second face ofsaid wedgeshaped portion when the engine temperature rises above saidgiven value, said second face of said lever wedgeshaped portion being atleast substantially perpendicular to the path of travel of said stripouter end for said given position of said lever, and said spring meansbeing arranged yieldingly to oppose the rotation of said lever producedby the push of said strip outer end on said second face of said leverwedge-shaped portion during a lowering of the engine temperature.

References Cited by the Examiner UNITED STATES PATENTS 627,390 6/99Cash. 1,715,327 5/29 Ivanhoif 236-48 X 2,011,546 8/35 Waltenberg 236482,834,586 5/58 Szwargulski 26139 2,946,577 7/60 Dennison et al 261-39HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner.

1. IN A CARBURETTOR FOR AN INTERNAL COMBUSTION ENGINE, AN AUXILIARYDEVICES OF THE TYPE DESCRIBED WHICH COMPRISES, IN COMBINATION, A FRAME,A CHOKE VALVE MOVABLY CARRIED BY SAID FRAME FOR VARYING THE FUEL RATE OFTHE FUEL AND AIR MIXTURE SUPPLIED BY SAID CARBURETTOR, SAID CHOKE VALVEHAVING A CLOSED POSITION WHERE THE FUEL RATE IS LOWER, MUM AND AN OPENPOSITION WHERE THE FUEL RATE IS LOWER, A BIMETALLIC SPIRAL STRIPRESPONSIVE TO VARIATIONS OF SAID INTERNAL COMBUSTION ENGINE TEMPERATURE,SAID BIMETALLIC SPIRAL STRIP BEING FIXED AT ITS INNER END TO SAID FRAMEABOUT AN AXIS, THE OUTER END OF SAID BIMETALLIC STRIP BEING MOVABLE WITHRESPECT TO SAID FRAME BETWEEN A COLD STATE POSITION AND A HOT STATEPOSITION ALONG A GIVEN PATH OF TRAVEL, SAID BIMETALLIC STRIP OUTER ENDBEING OPERATIVELY CONNECTED WITH SAID CHOKE VALVE FOR GRADUALLY OPENINGSAID CHOKE VALVE FROM ITS CLOSED POSITION WHEN SAID TEMPERATURECORRESPONDS TO THE ENGINE BEING COLD TO ITS OPEN POSITION WHEN SAIDTEMPERATURE HAS RAISED TO A GIVEN VALUE, A LEVER PIVOTED TO SAID FRAMEABOUT AN AXIS PARALLEL TO SAID FIRST MENTIONED AXIS, SAID LEVER HAVING AWEDGESHAPED PORTION ADAPTED TO COOPERATE WITH SAID STRIP OUTER END ANDLOCATED BETWEEN THE COLD STAGE POSITION AND THE HOT STATE POSITION OFSAID BIMETALLIC STRIP OUTER END, SAID WEDGE-SHAPED LEVER PORTION HAVINGA FIRST FACE TURNED TOWARD SAID BIMETALLIC STRIP COLD STATE POSITION,AND A SECOND FACE TURNED TOWARD SAID BIMETALLIC STRIP HOT STATEPOSITION, SAID STRIP BEING SO ARRANGED THAT ITS OUTER END IS OUT OFCONTACT WITH SAID LEVER WHEN THE ENGINE IS COLD AND IS APPLIED AGAINSTSAID FIRST FACE OF SAID LEVER WEDGESHAPED PORTION WHEN THE ENGINETEMPERATURE HAS RAISED TO SAID GIVEN VALUE SO THAT SAID STRIP OUTER ENDCAN SLIDE ALONG SAID FIRST FACE AND BEYOND IT TO SAID SECOND FACE OFSAID WEDGE-SHAPED PORTION WHEN THE ENGINE TEMPERATURE RISES ABOVE SAIDGIVEN VALUE, SAID SECOND FACE OF SAID LEVER WEDGE-SHAPED PORTION BEINGAT LEAST SUBSTANTIALLY PERPENDICULAR TO THE PATH OF TRAVEL OF SAID STRIPOUTER END FOR SAID GIVEN POSITION OF SAID LEVER, AND SPRING MEANSCARRIED BY SAID FRAME ADAPTED RESILIENTLY TO URGE SAID LEVER IN THEDIRECTION OPPOSED TO THAT IN WHICH IT IS PUSHED BY SAID STRIP OUTER ENDMOVING FROM ITS HOT STATE POSITION TOWARD ITS COLD STATE POSITION, SO ASYIELDINGLY TO OPPOSE THE ROTATION OF SAID LEVER PRODUCED BY THE PUSH OFSAID STRIP OUTER END ON SAID SECOND FACE OF SAID LEVER WEDGE-SHAPEDPORTION DURING A LOWERING OF THE ENGINE TEMPERATURE.